Meter shunt preventing means



1936. LE ROY SEARCH METER SHUNT PREVENTING MEANS Filed Dec. 29, 1933 9a84 I2 l4- lNVENTO/i Le/FoySeafc/v HTTURNEY Patented Oct. 6, 1936 UNITEDSTATES PATENT OFFICE 3 Claims.

This invention pertains to means preventing by-passing of current aroundan electric energy recording meter whereby unrecorded electrical energymay be obtained.

Electric power dispensing companies are increasingly confronted with theproblem of preventing current stealing, two of the most common forms ofsecuring unrecorded energy being the use of a U shaped jumper insertedso as to directly contact the meter terminals or relatively minutecontacts projected through the insulation of one of the power leads andthrough the insulation of the corresponding load line.

The various types of watt-hour meters whether of the Thomson type or themercury flotation type operate in a generally similar manner andcomprise a small motor whose instantaneous speed is proportional to thepower passing through it, and whose total revolutions in a given timeare proportional to the total energy or watthours delivered during thattime. One side of the line is connected in series with the field coilsand the armature is connected across the line, the retarding torquebeing provided by a disc such as aluminum rotating between a magneticfield of constant strength.

Obviously if the current is shunted around the field coils as previouslydescribed the meter will run slow and only a relatively small amount ofenergy will be recorded.

Although various means to effect retarding of the disc movement areemployed the aforementioned means are the most widely used and mostdifiicult to detect and combat.

I have devised a means of rendering the aforementioned methodsineffective for the purpose desired and whereby the fuses controllingthe power lines will be blown.

It is the object of my invention therefore to provide a means preventingunauthorized consumption of electrical energy.

Another object of my invention is to render the power lines inoperativewhen an effort is made to shunt current around the meter.

Another object of my invention is to provide improved means preventingaccess to the meter terminals.

Other objects of the invention and the invention itself will becomeincreasingly apparent from a consideration of the following descriptionand drawing wherein Fig. l is a preferred embodiment of my invention asapplied to a conventional two wire system; Fig. 2 is a wiring diagram ofthe construction illustrated in Fig. 1; Fig. 3 is a side elevationalview of the embodiment shown in Fig. 1.

Fig. 4 is an enlarged fragmentary view of terminals which I may employin connection with the embodiment illustrated in Fig. 1;

Fig. 5 is an enlarged fragmentary sectional view taken along the line5-5 of Fig. 1;

Fig. 6 is a fragmentary elevational view of a modification of myinvention as applied to a three-wire system and Fig. 7 is a wiringdiagram of the three-wire system illustrated in Fig. 6.

Referring now to the drawing I have shown at I a conventional watt-hourmeter which may be either of the Thomson or mercury flotation type andhaving contacts 2 and 3 extending from the power line terminals, andcontacts 4 and 5 extending from the load line terminals. The contact 2is connected to a power line externally of the building through aterminal 6, line I, one pole 8 of a two pole switch, fuse 9, and lineIII. Contact 3 is connected to the external power line through terminalII, line I2, the other pole 8a of the switch, fuse 9a, and line I3.Contact 4 connects with the load line It through terminal I5 and contact5 connects with load line I6 through terminal II.

The terminals and contacts are disposed within a preferably box-shapedstructure generally indicated at I8 and formed of bakelite or othersuitable insulating material, the box I8 being flush with the rear wallof the meter and secured to a suitable support I9 by any desirable meanssuch as bolts 20 projected through the base of the structure andengaging the support. The box I8 is provided with upstanding sides of auniform height and is cut away as indicated at 2| to closely engage theportion of the meter base disposed therein.

The base of box I8 has upstanding ribs as indicated at 22 integraltherewith and adapted to act as insulating mediums preventing contact ofthe terminals 6, II, I5 and I1. outwardly of terminals 6 and I! aredisposed ribs 2323 abutting the base of the meter and preventing wireswhich might be inserted intermediate the meter and box I8 despite theirabutting relationship from engaging terminals 6 and H or contacts 2 and5.

The lines I, I2, I4 and I6 are projected upwardly to engage theirrespective terminals through perforations provided therefor in thebottom wall of box I8. I contemplate that the aforementioned lines willmake a sufficiently tight engagement with box I8 to prevent wires or thelike being projected through the box to engage the terminals but as willbe hereinafter described should such wires be so projected they will beineffective to obtain the desired result of shunting current around themeter.

Lines I and I6 are connected in series with the field coils of the meterand consequently these are the lines which are inter-connectedexternally of the meter or at the meter terminals to shunt out the fieldcoils. Inter-connecting any other combination of lines externally of themeter or at the meter terminals would cause a. direct short blowing thefuses or would be ineffective to shunt out the field coils andaccomplish the desired result.

I provide a relatively thin conducting sheath 25 preferably formed ofcopper braid which is telescoped over the insulation of line I as bestillustrated in Fig. 5 the sheath 25 in turn being covered with similarinsulating material 26. The sheath being relatively thin does not addmaterially to the diameter of the conduit and if desired both powerlines 1 and i2 may have substantially the same outside diameter.

Although a slight difference in diameter would not lead to the suspicionthat either wire was other than the conventional lead in wire. Thesheath 25 extends the entire length of line 1 being projected throughthe fuse box at one end and the box 18 at the other end although it doesnot contact line 1 at any point. Internally of box I8, sheath 25 isextended beyond the outer insulating sleeve as illustrated in Figs. 1and 5 and is gripped by a resilient collar 27 having an upwardlyextending arm 28 which engages terminal II. The collar 21 may havesufiicient inherent resilience to be sprung around sheath 25 or may beclamped therearound in any suitable manner and is of sufiiciently largediameter to prevent any wire or the like which might be projectedthrough the perforation provided for conduit I from contacting terminal5.

The conduit Ill is preferably of a construction similar to conduit 1 andthe conduits 1 and Ill are connected internally of the switch box with aconducting line 30. Lines in and I3 are projected through the foundationor walls of the building to connect with the outside power lines. It isunderstood that the conducting sheath encircling the power line ofconduit I 0 need only be carried outside the building.

The box i8 is provided with a cover 3| of bakelite or the like, thecover being pivotally fixed to box l8 as indicated at 32 and afterinstallation the cover is sealed to the box by seals indicated at 33 and34 projected through aligned perforations in lugs provided on the boxand cover. In a similar manner a cover (not shown) is sealed to the fusebox by seals 35 and 36.

Although I have shown a particular type of fuse box I contemplate that atype of box may be employed whereby the fuses may be replaced withoutunsealing the box.

The operation of the device is as follows: if employing a U type jumperone leg of which might possibly contact terminal H, the other leg wouldcontact collar 21 thereby effecting a short across lines I2 and I6 andblowing the fuse. The same result would occur if contacts were attemptedto be projected through the insulation of lines l6 and 1 since thecontact at line I would contact the sheath 25 rather than the power lineand the fuse would be blown. If lines Ill and I3 were tapped the onlyefiect would be to put one side of the line in series with the topcontacts without a return line or if the top contact engaging conduit H!were projected through the sheath to engage the power line a shortcircuit directly across the lines HI and i3 would occur blowing fuse 9a.

Although I have shown conduit II) as being of a construction similar toconduit 1 it is understood that a conventional connection similar toline 13 might be utilized and the connection 38 dispensed with ifpreventive means at this point is not felt necessary.

In the ordinary hook-up of a meter and fuse box the length of conduitneeded such as I would be relatively small and in combination with boxI8 the above described means provides an efiective and inexpensive meansof preventing current stealing.

Referring now to Fig. 6 I have shown an arrangement generally similar tothat hereinbefore described as applied to a three wire system.

In this construction a box 50 is provided with terminals 5|, 52, and 53for the power leads, and terminals 54, 55 and 56 for the load leads.Power conduits 51 and 58 similar to conduit 1 are provided, the sheathportions thereof being connected to terminal 52 of the neutral line 59.In this construction one of the meter field coils is in series withpower conduit 51 and its corresponding load line and the other fieldcoil is in series with power conduit 58 and its corresponding load lineand if an attempt is made to shunt out these coils or either of them ashort circuit is effected across the lines resulting in the fuses beingblown. The wiring diagram for the threewire system is illustrated inFig. 7.

Although I have shown and described modifications of my invention Icontemplate that numerous and extensive departures may be made therefromwithout departing from the spirit of my invention and the scope of theappended claims.

Having thus described my invention what I claim is:

1. The combination with a first and second lead-in wire, circuitbreaking means associated therewith, an electrical energy recordingmeter including field coils, a first load line in series with the meterfield coils and first lead-in wire, and a second load line in serieswith the second lead-in wire, of a relatively thin protective conducting sheath encasing the first lead-in wire, insulated therefrom, andconnected to the second lead-in wire whereby a shunt inter-connectingthe encasing sheath and first load line around the meter coils willinterconnect the first and second lead-in wires to cause the circuitbreaking means to break the circuit.

a meter for recording energy taken from the current source, lead-inWires connecting the current source and meter, circuit breaking meansassociated with the lead-in wires, and load wires extending from themeter, of a flexible sheath of conducting material encasing one of thelead-in wires and connected to another lead-in wire whereby an attemptto shunt the meter coils by inter-connecting a lead-in wire and loadwire in series therewith will inter-connect the lead-in wires to causethe circuit breaking means to break the circuit.

3. The combination with lead-in wires, circuit breaking means, a sourceof current, and an electrical energy recording meter, of a relativelythin flexible sheath of conducting material extending from the circuitbreaking means to the meter encasing one of the lead-in wires, insulatedtherefrom and connected to another leadin wire whereby a connectionformed with the encasing sheath and a conductor in series with theencased lead-in wire will interconnect the lead-in wires to cause thecircuit breaking means to break the circuit.

LEROY SEARCH.

